1. Field of the Invention
Pallet tier cap forming apparatus for forming into a pallet tier cap a horizontal planar paperboard blank including a generally rectangular center panel having four edges, and four flaps connected by fold lines with said center panel edges, respectively. A blank transport device initially displaces the blank laterally in a first diagonal direction to break simultaneously downwardly a first pair of flaps. The blank is then displaced laterally in the opposite diagonal direction, and the forming steps are repeated to fold downwardly simultaneously a second pair of flaps.
2. Brief Description of the Prior Art
Tier sheets are used between layers of palletized products to distribute the load and prevent cases from an upper layer from concentrating their force and crushing cases on a lower layer. Examples of apparatus and methods for forming and handling such pallet tier sheets are shown by the patents to Winski et al U.S. Pat. No. 5,336,042, Lerner et al U.S. Pat. No. 4,955,177, and Iwaki et al U.S. Pat. No. 4,400,929, and the Ouellette et al patent application publication No. US 2008/0122160.
Often cases do not have lids as a lid is redundant product protection if a tier sheet covers the layer. When lidless cases are palletized a tier cap sheet is often used to stiffen the edges of a tier sheet and prevent upper layer cases from bending the edge of a tier sheet down into a lower level case. A cap tier sheet must have its flaps broken down or up and those flaps must remain broken less than 180 degrees to provide rigidity to the edge of the tier sheet. For an automated palletizing machine, the flaps must be automatically bent.
One method for bending the flaps is to hold a single tier cap from the top in a suspended position, actuate a plate to hold the tier cap up just inside the intended break line, then actuate a plate to come down and break the flap downwardly. This operation is repeated on all four sides to the tier cap until all four flaps are bent down and enough memory remains that they do not spring back to 180 degrees. This method and apparatus is time consuming and requires expensive actuators. The resulting bend angles from this method and apparatus are marginal as the bending action does not initially force the bend to less than approximately 60 degrees and when the flap bends back out it often goes back to almost 180 degrees. The time this method and apparatus takes is often unacceptable for an automated palletizing cell. Palletizing cells are typically designed to keep up with case production plus a safe margin to ensure the palletizing cell is not the bottleneck in the production line. The additional time for bending four flaps on a tier cap at every layer slows the overall processing time down considerably.
Therefore, the prior art machines have the drawbacks that a tier cap sheet on an automated palletizing cell can be very expensive to implement, provide inadequate bending of the flaps, and may take too much time to allow for full automation.